Fascinating: attempt to disentangle visibility bias versus self-promotion bias. I.e., compare whether it's because the papers are more visible, or whether it's because these same people are also likely to promote elsewhere.
- Michael Nielsen

I would guess the other peak is a timezone effect of some sort - but it seems early for American timezones
- Cameron Neylon

Self-promotion effect is a significantly larger effect, although the visibility does help.
- Michael Nielsen

closer look at the graph - looks like a North American and European midday hump to me
- Cameron Neylon